In this work, TiO2 nanoparticles were successfully synthesized with narrow size distribution via a wet ball milling sol-gel method. The effect of calcination temperature on photocatalytic activity was observed from particle size, crystallite size, and phase transition of TiO2 nanoparticles. Increasing calcination temperature increased particle size, crystallite size, and the crystallinity of synthesized TiO2. Phase transition depended on variation in calcination temperatures. A two-phase mixture of anatase and brookite was obtained with lower calcination temperature whereas a three-phase mixture appeared when calcination temperature was 500–600 °C. With higher temperature, the rutile phase kept increasing until it was the only phase observed at 800 °C. Anatase strongly affected the photocatalytic activity from 300 °C to 600 °C while the particle size of TiO2 was found to have a dominant effect on the photocatalytic activity between 600 °C and 700 °C. A mixture of three phases of TiO2-600 exhibited the highest methylene blue degradation with the rate constant of 9.46 × 10−2 h−1 under ultraviolet (UV) irradiation.

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Titanium dioxide (TiO2) has been extensively studied as photo-catalyst for water treatment, air purification and antibacterial applications due to its challenging properties such as chemical stability, environmental friendly and strong photocatalytic activity. However, the limitation of TiO2 on its dependent to ultraviolet radiation for photocatalytic activity is still aroused. In this study, silver doped titanium dioxide (Ag-TiO2) was synthesized by wet-ball milling sol–gel method (WBMS). Ag-TiO2 molar ratio was varied from 0% to 10% to study the effect of silver content on the synthesized Ag-TiO2 characteristics and the ability to apply on antibacterial applications. The objective of this work was to find an optimal concentration of Ag in Ag-TiO2. Characterization of the particle size, morphology, and surface area of synthesized Ag-TiO2 were discussed by techniques of transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET). Photocatalytic activity was investigated from degradation of methylene blue. Antibacterial activity was conducted by finding minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests performed on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) under dark condition and under visible light. The results demonstrated that the doping of Ag inhibited crystal growth of Ag-TiO2. The smallest particle size and the highest surface area were obtained from 5% Ag-TiO2. Also, it was found that methylene blue degradation rate increased to the highest number of 1.62x10−3 min−1 when Ag concentration reached 5%, and methylene blue degradation rate reduced when Ag concentration was higher than 5%. The antibacterial activity of Ag-TiO2 was better than TiO2. The optimal concentration of 3-5% Ag-TiO2 was observed from the MIC and MBC tests.